The present invention relates to a multidose delivery pump provided with means for the removable coupling with the neck of a container filled with a liquid, particularly adapted to deliver variable doses of food ingredients or detergents.
It is known that hygienic and practical requirements resulted in a considerable spread on the market of containers for liquids provided with distributors or delivery means to be actuated manually by the user.
The known delivery pumps substantially comprise a hollow body defining a suction and compression chamber and provided with a liquid suction duct.
A tight piston is slidingly coupled to the hollow body and internally provided with a liquid delivery duct communicating with outside and the suction and compression chamber.
Valve means generally consisting of metal balls, are arranged downstream and upstream the suction duct and the delivery duct respectively, and regulate inflow and outflow of the liquid to and from the suction and compression chamber.
Elastic means generally consisting of spiral springs, are also arranged between the hollow body and the piston and provide for the piston return to the rest position when the delivery is over.
In operation the user acting on the piston loades the elastic means and compresses the liquid contained in the suction and compression chamber at the same time opening the delivery duct and allowing the outflow of the liquid to the outside.
When the tight piston reaches the bottom of the suction and compression chamber, it is released by the user so as to allow the elastic means to return the piston to the starting rest position.
The elastic return of the piston generates a vacuum inside the suction and compression chamber, opening the liquid suction ducts and closing the delivery duct so as to allow inflow of liquid inside the chamber and preparing the pump for the next delivery.
A duct communicating with outside allows to restore the pressure inside the container.
It is important to note that the maximum amount of liquid to be delivered is substantially equal to the volume of the suction and compression chamber and is proportional to the stroke travelled by the piston under the action of the user. A first drawback of the above mentioned delivery pump of known type above mentioned consists in that the pump delivers when used in the traditional way, a fixed amount of liquid equal to the volume of the suction and compression chamber.
Indeed when the user needs a smaller quantity of liquid, he must manually control in a sensorial way his action on the piston by releasing it in advance as soon as the desired quantity of liquid is reached.
This is particularly important when the liquid to be delivered is for instance a sauce such as ketchup, mustard or the like.
Another drawback linked to the preceding one consists in that to cover the market demand, the manufacturers must make several different models of pumps which differ only for the amount of liquid that can be delivered.
This involves a considerable increase of the number of models to be manufactured with a consequent increase of problems of production and management of the whole production cycle and stockage of the pump.
Another drawback consists in that the elastic means are generally metal spiral springs which prevent a direct recycle of the pump which is possible only after a previous separation of the members made of metal materials from the members made of plastic material.
The object of the present invention is to overcome the foregoing drawbacks. More particularly a first object is to provide a delivery pump that with the same components allows to deliver predetermined amounts of liquid by actuating the pump in a non-sensorial way, causing the piston to reach always the stroke end.
Another object is to provide a pump whose quantity to be delivered is predetermined at the time of assembling the pump or applying it to the container.
Another object is to provide a pump whose quantity of liquid to be delivered may be regulated also by the user in a simple, quick and precise way.
Another object is to provide a pump that after its use can be immediately and fully recycled without any previous disassembling operation or the like.
Another object is to provide a pump which is particularly easy to be used and reliable.
A last but not least object is to provide a pump which is particularly cheap and of easy construction and assembling, suitable for the mass production
The above mentioned objects are attained by a delivery pump provided with means for the removable coupling to the neck of a container for the liquid to be delivered the main features of which are according to claim 1.
Advantageously as the delivery pump of the invention can vary the piston stroke, it allows to reduce considerably both the production and stockage cost due to pumps of different capacity. Indeed the pump allows to combine in a single pump, models with different characteristics of delivery.
Still advantageously the invention allows the user to actuate the pump always at the stroke end so as to obtain the precise quantity of liquid selected without being compelled to operate in a sensorial way on the piston as it happens now for the known pumps.